You should fill the Resources collection manually:

protected void Page_Load(object sender, EventArgs e)
{
  // I assume that resources are loaded in dtResources DataTable
  foreach (DataRow dr in dtResources.Rows) {
    DayPilotScheduler1.Resources.Add(new Resource(dr["name"], dr["id"]);
  }
}

The Resources collection is stored in the ViewState so it's possible to place this init code inside if (!IsPostBack) block. However, the ViewState for DayPilotScheduler is usually very large - I recommend turning it off and placing the initialization code outside of if (!IsPostBack).

Do you mean that it is best to turn off the view state for the scheduler control?

Yes:

1. It stores all the events. That is convenient sometimes (you don't have to rebind after CallBack/PostBack) but it means that all events are sent twice to the client (once inside ViewState and once in JSON object). But what's worse, it's also sent back with all requests (PostBacks/CallBacks).
2. It's not necessary to turn ViewState off until you see the slowdown. But it's the first thing you can do to improve performance.